This is a topic that I’ve been interested in. Basically, we could divert the great ocean currents, by means of floating curtain barriers, moored in the deep oceans. Take Couthern California. So Cal suffers because a cold ocean current (the Alaska Current) runs south along the coast. This produces the dank fog that hangs over the coast in the summer. It also means that So Calis an arid desert-the local rainfall would increase greatly if the ocean were to warm up (and increase evaporation). My proposal would be: starting at the Farallon Islands (off San Franciso), a chain of bouys would suspend 1000 foor dep curtains , down into the ocean depths. These would extend for 200 miles to the west, ant a SW- angle. This would divert the Alaska Current to the Southwest, and warmer water would then move up the coast from Mexico. Probably, the surface water temperature would increase from the present 55 F to over 70 f. As I said, So California would then experience:
-clear summer days, with less fog/overcast
-much higher rainfall
This sounds like a plan to me…would it work? 
One of the first effects would be a massive die-off in ocean and costal plants and animals. It would destroy unique ecosystems.
No I don’t think this is a good idea even if it were feasible.
I’m sure it could be done, but I think it would have far-reaching environmental effects; much of the local fauna will be dependent on those cold currents, I’d wager, so diverting them couold have a massive cascade effect on the food chain, including the human aspects of it.
The hardware would have to be pretty substantial too; we’re talking about a huge volume of moving water - it’ll just tear through a curtain, or rip out the anchor points.
And then there are the effects of that greater rainfall - is the local drainage up to scratch, or would it cause flash floods and major loss of life? What if diverting the current results in a stable, but different configuration? The knock-on effects might be quite spectacular.
It probably could be done though, in terms of engineering, but predicting the likely outcome is far from simple.
What goes for the inside of the head, goes for ocean currents. Given their connections to weather patterns, changing them is a bad idea, because “You never know what it might be attached to.”
I agree that we might see some bad consequences, but we are doing nothing permanent here-the curtains could be raised, and the experiment terminated at any time (should things go wrong).
As for you in the UK…watch out! I plan to alter the Gulf Stream current…I want to divert it more to the west, so that it will warm up NE and Greenland.
Of course, you folks in the UK might have to buy some snow plows, but heck, “lets gove it a go!”
Nothing permanent? Potential extinction of species, destruction of habitats, death and injury during massive floods?
There is also (as I said) the possibility that the diversion ends up creating a new, stable, but extremely undesirable, configuration of currents.
The effect of altering ocean currents would very possibly be the destruction of Western civilization, the deaths of billions of people in the ensuing chaos and warfare, and misery on a scale unsurpassed by even the imagination.
So I guess it’s probably not a good idea.
Man, talk about the butterfly effect in magnitude. :eek:
Not to mention who’s paying for this little experiment.
How much $$$ might we talking about?
The potential lawsuits by areas affected would be enough to stop any project before it started.
We can’t even damn up a stream that might kill a species of minnow or cut a tree that is home to a spotted owl and you wanna do what? 
Stop giving the terrorists ideas!
Messing with ocean currents does more than simply affect local climate - it affects global climate. And global climate changes have been implicated in several instances of mass extinction throughout geologic time. What you get out of this sort of project would likely be very different from what you’d like to get out of it…
Never disturb a chaotic system unless you’re in really deep shit already. I’d say we aren’t to the point where we need to take risks on global climate shifts and mass oceanic extinctions just yet. Certainly not to just get nicer weather for a few coastal cities.
Alternate method:
Drill a giant hole in the ocean floor until you hit magma, then let that bad boy go to work!
Right. We’ll get to work on that just as soon as we perfect the concept of dissipating hurricanes with thermonuclear weapons.
Or, else, it seems it would be near-infinitely easier and cheaper to just move to a place with better weather.
What’s next, try to weld together the North American and Pacific tectonic plates from California to Alaska?
That would put the wall of China to shame, the weld of America!
More rain in Southern California would enlarge the Salton Sea, and perhaps cause the Imperial and Death Valleys to fill up. LA would not fair well in that case.
We have been modifying the climate of So. California for decades! Take the importation of water from the Owens valley, and the Colorado River (so that people in LA can water their lawns)!
Really, I can see many benefits from a warmer, wetter So. California:-WE can grow the whole nations’ food supply in the So. California desert.
The Salton Sea can be enlarged, and restored as a major fishing resort.
-the ocean fisheries of So. California arenot particularly productive right now (surface water is too cold). Warmer surface water will bring in more and better species of food fish.
Yeah, the sea lions might have to move North, but so what?
You are aware that, in essence, the El Niño effect on S. CA is due to warmer surface waters off the coast and is associated with storms, mudslides, etc. that cost millions of dollars and many lives? Not to mention a negative effect on the fisheries and productivity of coastal ecosystems?
Why do we want to do this, again?
I dunno. Something to do with foggy mornings during the summer.